Scientific Method —

Biorefineries challenge petrochemicals with engineered yeast

A session at this year's AAAS discussed how far we've come in using …

The first session I attended as part of this year's AAAS meeting focused on the state of the art in, and technological hurdles that limit, biorefineries. An analog to common petrochemical refineries, biorefineries are facilities that create fuel, power, and chemicals from biomass precursors, as opposed to the more traditional petrochemical precursors. They offer a route toward a more renewable and green industrial future, but they do not have the nearly century's worth of history, research, and success behind them that their counterparts do.

The session, titled "Biorefinery: Towards an Industrial Metabolism," opened by describing a biorefinery as "a unique cross-fertilization between 'industrial metabolism' and 'systems biology.'" The first talk, given by Jens Nielsen from Chalmers University of Technology, focused on work his research group has been undertaking using yeast as a cellular factory for producing a variety of biochemicals. The unit operation of interest here, since yeast was the focus, was fermentation. To start the talk, Nielsen listed off a large list of common stock chemicals that can be created by fermentation; the real trick, however, is to make a specific chemical rather than an amalgam of byproducts.

Highlighting a problem that had been solved in his lab, Nielsen discussed the creation of yeast cells that were engineered to specifically produce succinate, an important precursor chemical in a number of products. First, they used simulations to determine what genes to manipulate to engineer a yeast that coupled succinate production with growth. Using these results and traditional genetic manipulation techniques (yes, we are living in the future people!) they were able to create a mutant yeast that could produce succinate—but as a downside, required glycine to live.

To get around this hurdle, they evolved a strain of the yeast over successive generations to live off less and less glycine. From the collection of these yeasts, they selectively cultured those that were the fastest growers. In the end, they had their desired engineered yeast: it required no glycine input, and coupled succinate production to yeast growth. These cells could now be used as the key step in a bio-based succinate production reactor.

As a form of a real-world counterpoint to the Nielsen's advancements, the next speaker, Anne Wagner from SYRAL, discussed the use of biorefineries in industry today. While academia has all the time in the world to research new techniques and processes, shareholders in industry demand faster returns on investment and must use what is available at the time.

SYRAL uses wheat- and corn-based feedstocks to produce chemicals for a variety of industries such as food applications, chemical and building supplies, paper and cardboard, and animal nutrition. Wagner highlighted the extremely capitalistic nature of the business, pointing out that the bottom line is constantly on somebody's mind.

Raw materials (corn and wheat) cost $1.30 per kilogram and can account for up to 55 percent of the total cost of the final product. The actual amount that the final product can sell for depends on the amount of processing and refining that is carried out—the more work that is put into it, the higher the final value. High-value products such as fine chemicals still cost more than twice as much as they would if one went through a more traditional petrochemical route. Often, companies are unwilling to spend, or charge, the extra premium needed to carry out these processes in a sustainable green manner; cost is the ultimate driver.

As Wagner pointed out, to make these biorefining routes palatable to the bean counters at large chemical companies, there needs to be two things: technology with higher yields, and regulatory incentives that will help make these sustainable processes possible at the industrial scale.

The final talk of the session was given by James Clark from the University of York. His talk was titled "green chemistry and the biorefinery," and focused on the underlying message that pervaded the session: the need for sustainable and reusable chemical production methodology. Clark hammered the point that biorefineries should not focus solely on fuel production (bioethanol), but also include chemical production as well—just like traditional petro-refineries.

Another major talking point of Clark's was the use of more sustainable raw materials; he highlighted the short lifespan of known elemental resources around the periodic table and the globe. He stated emphatically that the "biggest source of future elements is waste."

To extend our supply of raw materials, Clark argued that we must also find new uses for old materials; he highlighted the transformation of plain old starch into expanded starch, which has found uses in a variety of applications, including carpet tiles found in some houses. A separate session, attended by my colleague Dr. Gitlin, focused solely on waste as the world's largest resource (it will be covered in the coming days).

This session emphasized three facets of using bio-production techniques. First, they reduce the amount of nonsustainable raw materials we need if we're to create the things that we take for granted in first world countries. Second, through modern chemical and genetic engineering, we are capable of creating entire lifeforms that can produce a chemical for us (the future!). Finally, before these methods will be accepted by corporations, they need to be more reliable and, more importantly, cheaper, generating more money before people begin to take them seriously.

Matt Ford
Matt is a contributing writer at Ars Technica, focusing on physics, astronomy, chemistry, mathematics, and engineering. When he's not writing, he works on realtime models of large-scale engineering systems. Emailzeotherm@gmail.com//Twitter@zeotherm

the glycine story was a bit amusing: breeding engineered yeast, but using traditional mendelian methods, nothing recombinant. I wonder if the luddites among the anti-GMO crowd would be mollified by this approach - it would be even funnier if we wound up with non-recombinant engineered corn. (corn is harder to breed than yeast, I suppose...)

Are they using special corn and wheat? Otherwise it costs a lot less than that.

Quote:

Finally, someone realizing that trash is actually useful.

It's not really the first time. Based on things I've seen previously, we should probably give up on domestic recycling for now. Just store all the trash in landfills until we have more efficient ways of recovering as much as possible.

It's not really the first time. Based on things I've seen previously, we should probably give up on domestic recycling for now. Just store all the trash in landfills until we have more efficient ways of recovering as much as possible.

I thought that was our plan, steal(buy cheaply) as much as we can from china, and then store the excess in places called landfills until we really need it.

Are they using special corn and wheat? Otherwise it costs a lot less than that.

Quote:

Finally, someone realizing that trash is actually useful.

It's not really the first time. Based on things I've seen previously, we should probably give up on domestic recycling for now. Just store all the trash in landfills until we have more efficient ways of recovering as much as possible.

It's the cost of buying 2kg bags at the supermarket and hiring someone to open them and pour the flour down the chute

1) these folks are big business too, so it's not like some kid in his basement vs. Dow chemical. They are both industrial

2) I'm a fan of them beating established processes on price. Hopefully it will happen, and everybody will benefit from the improved production possibilities curve. However, if somebody says "It's green but costs more", be very suspicious. Things that cost more consume more inputs, and often that means they only look green on the surface.

@hobgoblin: That's obviously pretty far sci-fi. I imagine that just getting a nanomachine to recognize (let alone grab onto) a vibrating, conformation-changing molecule is incredibly hard. e.g. Julius Rebek Jr. has managed to trap some molecules in 'capsules', but not yet do anything with them -- and that's fairly state-of-the-art AFAIK.

That's why using microbes sounds more resonable; life has solved that problem (albeit in a slow and messy manner) via genes, proteins, and evolutionary mechanisms. Harnessing selection (as was done with the yeast in the article) seems a much easier route than building 'bots' from scratch.

i guess it depends on how wide a definition of nanobot one works with. In the widest sense, even using tailored microbes may be seen as a kind of programmed nanobot. This because they get built for a human need rather then by a need for survival (tho i guess it can be seen as one and the same, as the human need will be linked to the survival system of said microbe).

I'd imagine something more like using concentrated solar to reform all the organic material into fuel. Then concentrated solar again using traditional refinig to remove the easy big stuff like iron. And again more refining like arsenic to remove gold, and so on.